KR20110096503A - Surface protective film - Google Patents

Abstract

The surface protection film 10 which is excellent in adhesiveness with respect to a to-be-adhered body, and is small in the difference of peeling force by the surface state of a to-be-adhered body is provided. The surface protection film 10 is equipped with the acrylic adhesive layer 2 on one side of the support body 1, and satisfy | fills the following conditions: The laminated body 20 which laminated | stacked 24 sheets of protective films 10 of 0.195 MPa The ratio of thickness reduction (indentation distortion) E1 when compressive stress was applied for 10 minutes is 7.0% or more, and the ratio of E1 to thickness reduction ratio (permanent distortion) E2 remaining after 10 minutes after releasing the stress. (E1 / E2) is 30 or less; And peeling force S1 with respect to a plain TAC polarizing plate is 2 times or less of peeling force S2 with respect to AG-treated TAC polarizing plate.

Description

Surface protection film {SURFACE PROTECTIVE FILM}

This application claims the priority based on Japanese Patent Application No. 2010-036328 for which it applied on February 22, 2010, The whole content of this application is integrated in this specification as a reference.

This invention relates to the surface protection film provided with the film-form support body and the adhesive formed on the said support body, and is bonded to a to-be-adhered body and protects the said to-be-adhered body.

The surface protection film (also called a surface protection sheet) generally has a structure in which an adhesive is formed on a film-like support (base material). Such a protective film is bonded to a to-be-adhered body through the said adhesive, and is used for the purpose of protecting this to-be-adhered body from a scratch and contamination at the time of processing and conveyance. For example, the panel of a liquid crystal display is formed by bonding optical members, such as a polarizing plate and a wavelength plate, to an liquid crystal cell through an adhesive. A protective film is bonded to these optical members bonded to a liquid crystal cell through an adhesive for the purpose of preventing a flaw, a contamination, etc. The protective film is peeled off and removed from the optical member (adhered body) together with the pressure-sensitive adhesive in a step where the protective film is unnecessary because the optical member is bonded to the liquid crystal cell. As a technical document regarding a surface protection film, Unexamined-Japanese-Patent No. 2008-69261 and Unexamined-Japanese-Patent No. 2005-23143 are mentioned. Japanese Patent Application Laid-Open No. 11-116927 relates to a technique for improving the moisture permeability of an adhesive layer.

By the way, the peeling force at the time of peeling the protective film adhering to a to-be-adhered body from the said to-be-adhered body may differ by the difference in the surface shape of the to-be-adhered body, the polarity of surface composition material, etc. This is explained concretely, taking the case where an adherend is a polarizing plate as an example. Usually, the polarizing plate has a structure in which a protective layer made of triacetyl cellulose (TAC) is bonded to the polarizer made of polyvinyl alcohol (PVA) via an adhesive. A function is provided to this protective layer according to a use. For example, in order to reduce the glare caused by external light, antiglare (AG) treatment for forming fine unevenness is performed. Thereby, while the surface (TAC surface) of the polarizing plate (plane polarizing plate) to which such a function is not provided is smooth, the surface (AG surface) of the AG process polarizing plate (AG polarizing plate) becomes a surface which has unevenness | corrugation. There exists a tendency for the peeling force of a protective film to differ greatly in TAC surface and AG surface by such a difference of surface state (surface structure). In addition, the AG treatment is generally performed by coating (AG coating) on the surface of the TAC protective layer using a coating agent composed of a material having a lower polarity than TAC. As a result, the TAC surface is a smooth and relatively high polarity surface, whereas the AG coated surface (AG surface) becomes uneven and relatively low polarity surface. Such difference in chemical properties and difference in physical structure interact with each other, so that the difference in peeling force between the TAC plane and the AG plane becomes larger. Such a difference in peeling force may be a factor that lowers the efficiency of the work of peeling the protective film from the polarizing plate. Moreover, it is expensive to match peeling force by using a protective film according to the surface state separately.

Japanese Patent Application Laid-Open No. 2008-69261 discloses a pressure-sensitive adhesive composition due to the surface state of an adherend and the like, according to the pressure-sensitive adhesive composition containing a (meth) acrylic polymer copolymerized with a monomer having an alkylene oxide structure and a liquid ion salt. The thing which can be made small is described. However, this technique exhibits the above effects by using a liquid ion salt as an essential component (paragraphs 0061 to 0062 of the above publication). In the adhesive composition except liquid ion salt from the structure of the publication, it was confirmed that the effect of reducing the difference of adhesive force by the difference of surface state was not acquired. In order to realize non-contamination property to a to-be-adhered body at a high level, it is preferable to avoid the structure which makes use of a liquid ion salt essential. In addition, Japanese Patent Application Laid-Open No. 2005-23143 discloses a technique for reducing the peeling speed dependency of peeling force by decreasing the high-speed peeling strength, and reducing the difference in peeling force due to the difference in the surface state of the adherend. no.

In addition, the protective film requires a property (adhesiveness) to adhere well to the adherend to which the protective film is attached. When the protective film is in a state of floating from the surface of the adherend, when the adherend is subjected to an external force or a temperature change, the appearance of the adherend to which the protective film is bonded is caused by bubbles existing between the protective film and the adherend. Change. As a result, an apparent difference occurs between a portion that receives the external force and the like and a portion that does not receive, which causes a decrease in the precision of the appearance inspection, and furthermore, a factor in lowering the yield.

Since fine unevenness | corrugation is formed in AG surface of a polarizing plate as mentioned above, the protective film provided with the adhesive which is easy to deform | transform along the unevenness | corrugation (easy to fill in unevenness | corrugation) in order to adhere | attach a protective film well to the said AG surface is advantageous. By the way, generally, when adhesiveness with respect to the surface (for example, AG surface) which has a fine unevenness | corrugation improves, the difference of the peeling force of this uneven surface and smooth surface tends to become large. That is, the improvement of adhesiveness with respect to a to-be-adhered body, and the reduction of the difference of the peeling force by the surface state of the to-be-adhered body have the relationship that the other property will fall when the one characteristic is improved, and it was desired to make them compatible. .

Therefore, this invention is hard to produce the appearance change (difference of appearance) between the part which the said external force contacted and the part which did not contact even if it receives external force after bonding a protective film, and peeling force by the surface state of a to-be-adhered body An object of the present invention is to provide a surface protective film having a small difference.

According to this invention, the surface protection film provided with a support body and the adhesive layer formed in the one surface of the said support body is provided. The adhesive which comprises the said adhesive layer is an adhesive which uses an acryl-type polymer as a base polymer. The said protective film satisfies both the following conditions (A) and (B).

(A) Indentation distortion (E1) of the laminated body in which 24 sheets of said surface protection films were laminated | stacked is 7.0% or more, and the ratio (E1 / E2) to permanent distortion (E2) of the said indentation distortion (E1) is 30 or less Here, the indentation distortion (E1) is assumed that the initial thickness of the laminate is T0, and the compressive stress of 0.195 MPa was applied in a thickness direction for 10 minutes by inserting the laminate into a circular plane having a diameter of 8 mm at 25 ° C. It is the reduction ratio from the initial thickness T0 of the thickness T1 at the time (that is, E1 = (1-T1 / T0) × 100). Permanent distortion E2 is a reduction ratio from the initial thickness T0 of the thickness T2 when the initial thickness of the laminate is T0 and the laminate is released from the compressive stress for 10 minutes and elapses (that is, E2 = (1-T2 / T0) × 100).

(B) The said surface protection film is peeling force S1 with respect to the TAC polarizing plate (plane polarizing plate) which was not AG-processed in peeling force measurement performed on the conditions of measurement temperature 23 degreeC, peeling speed 30m / min, and peeling angle 180 degree. It is 2 times or less (namely, peeling force ratio S1 / S2 is 2 or less) with respect to this AG-treated TAC polarizing plate (typically, TAC polarizing plate with AG coating).

The surface protection film which satisfy | fills said (A) and (B) has little difference in peeling force by the surface state of a to-be-adhered body (in other words, there is little dependence on the to-be-adhered body of peeling force), and adhesiveness with respect to a to-be-adhered body surface This can be excellent. Such a surface protection film is suitable as a protective film used for the use of protecting the said optical member at the time of manufacture of an optical member (such as a polarizing plate for liquid crystal displays, etc.), conveyance, etc., for example.

In a preferable embodiment of the surface protection film disclosed herein, the pressure-sensitive adhesive layer after 30 minutes has elapsed by pressing the surface protection film on the AG-treated TAC polarizing plate (typically, TAC polarizing plate subjected to AG coating). The area exceeding 99.0% in close contact with the said polarizing plate. Since such a surface protection film shows the outstanding adhesiveness with respect to the uneven surface (for example, AG surface of a polarizing plate), even if it receives external force and temperature change, generation | occurrence | production of a float and its progression can be highly suppressed.

As the pressure-sensitive adhesive layer in the technique disclosed herein, in addition to the acrylic polymer, a oxypropylene unit preferably contains a compound (oxypropylene group-containing compound) having a polyoxypropylene segment in which two or more units are continuous. have. It is easy for the surface protection film provided with such an adhesive layer to satisfy said (A) and (B), and it is especially advantageous to satisfy said (B).

As an adhesive layer in the technique disclosed here, the adhesive layer which the said acrylic polymer was bridge | crosslinked with the isocyanate type crosslinking agent can be employ | adopted preferably. The surface protection film provided with such an adhesive layer tends to satisfy said (A) and (B), and it is especially advantageous to satisfy said (A).

It is suitable that the thickness of the said adhesive layer is 10 micrometers-40 micrometers, for example. The surface protection film provided with such an adhesive layer tends to satisfy said (A) and (B), and it is especially advantageous to satisfy said (A).

As the support, a polyester film having a thickness of 20 μm to 60 μm can be preferably used. It is easy for the surface protection film of such a structure to satisfy said (A) and (B), and it is especially advantageous to satisfy said (A). Moreover, since the surface protection film provided with the said support body has moderate elasticity and strength, it is preferable also from a viewpoint of handleability at the time of manufacture or use (adhering to a to-be-adhered body and / or peeling from an to-be-adhered body).

Moreover, as said support body, what consists of a synthetic resin film to which the antistatic process was given can be used preferably. Since a synthetic resin film tends to be electrostatic, the use of a synthetic resin film subjected to an antistatic treatment is particularly preferable in a surface protection film used for an application in which static electricity is to be prevented, such as an electronic device or a liquid crystal material.

BRIEF DESCRIPTION OF THE DRAWINGS The typical cross section which shows one structural example of the surface protection film which concerns on this invention.
It is typical sectional drawing which shows the other structural example of the surface protection film which concerns on this invention.
3 is a side view schematically showing the configuration of a sample for a compression creep test;
4 is an explanatory diagram schematically showing a method of a compression creep test;

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of this invention is described. In addition, matters other than what is specifically mentioned in this specification, matters necessary for implementation of this invention can be grasped | ascertained as the design matter of those skilled in the art based on the prior art in the said field | area. This invention can be implemented based on the content disclosed by this specification and technical common sense in the said field | area.

In addition, embodiment described in drawing is typical in order to demonstrate this invention clearly, and does not show the magnitude | size and scale of the surface protection film of this invention actually provided as a product correctly.

Surface protection film disclosed herein (for example, the surface protection film which protects the surface of the said optical component at the time of processing or conveyance of optical components, such as a polarizing plate and a wavelength plate. Typically used as a component of a liquid crystal display) The surface protection film used for an optical component) may be of the form generally called an adhesive sheet, an adhesive tape, an adhesive label, an adhesive film, etc. Although the said adhesive layer is typically formed continuously, it is not limited to this form, For example, the adhesive layer formed in regular or random pattern, such as a dot shape and stripe shape, may be sufficient. In addition, the surface protection film provided by this invention may be roll shape, or a sheet shape may be sufficient as it.

The typical structural example of the surface protection film provided by this invention is shown typically in FIG. This surface protection film 10 is provided with the sheet-like support body (base material) 1, and the adhesive layer 2 formed in the one surface (one side) 1A, and the surface of this adhesive layer 2 ( It is used by attaching 2A) to an adherend (a surface of an optical component such as a polarizing plate). The protective film 10 before use (that is, before adhesion to the adherend) typically has a surface (adhesion surface to the adherend) 2A of the adhesive layer 2 as shown in FIG. 2. At least the pressure-sensitive adhesive layer 2 side may be in a form protected by the release liner 3 having a release surface. Or the other surface (back surface of the surface in which the adhesive layer 2 is formed) 1B of the support body 1 becomes a peeling surface, and the protective film 10 is rolled up in roll shape, and the adhesive layer ( 2) may be in contact with each other and the surface may be protected.

The surface protection film disclosed here has 7.0% or more of indentation distortion (E1) with respect to indentation distortion (E1) and permanent distortion (E2) measured on predetermined conditions with respect to the laminated body in which the said surface protection film was laminated 24 sheets. In addition, it is characterized by the ratio E1 / E2 of the indentation distortion E1 to the permanent distortion E2 being 30 or less (characteristic (A)). Moreover, peeling force S1 with respect to TAC polarizing plate (TAC surface) which is not AG-treated is 2 times or less of peeling force S2 with respect to AG-treated TAC polarizing plate (AG surface), ie, peeling force ratio S1 / S2 is 2 or less It is characterized by (characteristic (B)).

Regarding the characteristics (A), the indentation distortion (E1) and the permanent distortion (E2) are measured by adding a compressive stress in the thickness direction to the laminate (test sample) under a measurement environment of 25 ° C. Subsequently, it performs by the compression creep test which releases the said stress. The structure of the sample used for the said compression creep test is shown typically in FIG. This sample 20 has 2 A of adhesive layer surfaces (adhesive surface) of the other surface protection film 10 on the support back surface (the other surface of the support body 1) 1B of one surface protection film 10 It is a laminated body of the form which laminated | stacked the surface protection film 10 of 24 sheets in total so that they may be bonded. It is preferable that these 24 surface protection films 10 have substantially the same area and shape. As an example of a preferred method of producing the sample 20, a method of preparing a laminate in which 24 surface protection films 10 of a suitable area are stacked and punching the laminate to a desired size (size corresponding to Sample 20) Can be mentioned.

The compression creep test can be performed using a jig having a circular plane (tip surface) having a diameter of 8 mm at its tip. For example, as shown in FIG. 4, the jig | tool (parallel jig | tool) 30 formed in the column shape of at least 8 mm in diameter in the vicinity of a front end can be employ | adopted preferably. The pair of front end surfaces 30A, 30B of the jig 30 are brought into contact with positions corresponding to both sides of the stacking direction of the sample 20 (state at the left end in FIG. 4). The distance between the front end surfaces 30A and 30B at this time corresponds to the thickness T0 of the sample 20 before the test (that is, the initial state).

From this state, the front end surfaces 30A, 30B of the jig 30 are brought close to each other, and the compressive stress in the thickness direction is applied to the sample 20 (state in the middle of FIG. 4). The size of this compressive stress is 1000 g per diameter of 8 mm (that is, the sizes of the end faces 30A and 30B) (corresponds to a pressure of 0.195 MPa). The state in which the compressive stress was applied is maintained for 10 minutes, and the thickness (thickness at the time of compression) T1 is obtained from the distances of the front end surfaces 30A and 30B at this time. Indentation distortion E1 is a reduction ratio of thickness T1 at the time of compression from initial thickness T0, and is calculated | required by following Formula: E1 = (1-T1 / T0) * 100;

After 10 minutes have elapsed from the provision of the compressive stress, the sample 20 is released from the compressive stress (state at the right end of FIG. 4), and the thickness T2 of the sample 20 after 10 minutes has elapsed from the release. Obtain This thickness (thickness after release) T2 is, for example, between the tip surfaces 30A and 30B when the tip surface 30A is gently brought into contact with the sample 20 held on the tip surface 30B. It can measure by distance. The permanent distortion E2 is a reduction ratio of the thickness T2 after release from the initial thickness T0, and is obtained by the following equation: E2 = (1-T2 / T0) x 100; In addition, in FIG. 4, the number of the surface protection films 10 which comprise the sample 20 is abbreviate | omitted and shown in order to make drawing easy to see.

Moreover, the magnitude | size of the said sample for compression creep test should just be a magnitude | size which can give a pressure (load) of 0.195 Mpa to the said sample, and is not specifically limited. For example, when using the jig | tool whose diameter of a front end surface is 8 mm as mentioned above, the bottom surface is the cause cylinder shape of diameter 8mm-15mm, and the bottom face is square shape of about 8mm-15mm Square pillar shapes and the like can be preferably employed. For example, similarly to the Example mentioned later, the measured value using the square pillar-shaped sample whose one side is 10 mm in one side can be employ | adopted as the value of E1, E2 in the technique disclosed here.

The large indentation distortion E1 means that the sample 20 is more likely to be deformed with respect to the external force. In general, most of the indentation distortion (E1) is due to the deformation of the pressure-sensitive adhesive layer 2, it can be said that the pressure-sensitive adhesive layer (2) is also easily deformable when the indentation distortion (E1) of the sample 20 is large. The surface protection film 10 provided with the adhesive layer 2 which is easy to be deformed so that indentation distortion (E1) may be 7.0% or more (may be 7.5 or more) at the time of adhesion to the surface which has fine unevenness | corrugation like AG surface By pressing on the surface (pressurized), the pressure-sensitive adhesive layer 2 can be well deformed along the irregularities. Although the upper limit of E1 is not specifically limited, It is normal to make E1 20% or less (for example, 15% or less) from the balance with other characteristics (for example, E1 / E2 mentioned later and pool repellency prevention property). It is suitable.

In addition, the fact that the ratio of the indentation distortion E1 to the permanent distortion E2 (E1 / E2, hereinafter also referred to as the “distortion recovery coefficient”) is small is that after the external force is removed, the residual force is removed after the external force is removed. This means that the distortion is relatively large (in other words, the distortion is difficult to recover). For example, the pressure-sensitive adhesive layer 2 of the surface protective film 10 having a large indentation distortion E1 can be deformed well along the irregularities when pressed against the surface having fine irregularities as described above, but the distortion recovery If the coefficient E1 / E2 is too large, the shape of the pressure-sensitive adhesive layer 2 released from the pressurization can be highly recovered before the pressurization (before the deformation along the unevenness), and thus the adhesion to the surface is lowered. On the other hand, even if the distortion recovery coefficient E1 / E2 is small, if the indentation distortion E1 is too small, the property of being deformed along the unevenness at the time of sticking initially is insufficient, and thus the adhesiveness is also lowered. According to the technique disclosed herein, the indentation distortion E1 is somewhat large (typically E1? 7.0%), and the distortion recovery coefficient E1 / E2 is somewhat small (typically, E1 / E2? 30) By this synergistic effect, the surface protection film which shows the outstanding adhesiveness also to the surface which has a fine unevenness | corrugation can be implement | achieved. It is preferable that E1 / E2 is 20 or less (more preferably 15 or less, for example, 10 or less). According to such a protective film, especially excellent adhesiveness (for example, adhesiveness of 99.5% or more) can be realized. Although the minimum of E1 / E2 is not specifically limited, Usually, it is three or more, and is typically five or more (for example, seven or more). The value of E2 may be, for example, about 0.1 to 3.0% (typically 0.2 to 2.0%).

About the said characteristic (B), the measurement of peeling force S1 and S2 is performed all on the conditions of 23 degreeC of measurement temperature, 30 m / min of peeling speed, and 180 degree of peel angles. More specifically, the measured value can be preferably used similarly to the peeling force measurement described in Examples described later (for example, by applying the same adherend, procedure, measurement conditions, and the like). Usually, the peeling force S1 with respect to a TAC surface is evidently higher than the peeling force S2 with respect to an AG surface. In the surface protection film which shows preferable indentation distortion E1 disclosed here, the value of peeling force ratio S1 / S2 tends to become especially high. For example, when the crosslinking density of an adhesive layer is made low (when the usage-amount of a crosslinking agent is reduced), indentation distortion E1 will become large and there exists a tendency for the peeling force from an adherend to rise. This increase in peeling force tends to have a greater influence on peeling force S1 on the TAC surface than on peeling force S2 on the AG surface. As a result, peeling force ratio S1 / S2 becomes large further.

Since the surface protection film disclosed here satisfies peeling force ratio S1 / S2 <= 2, there is little difference in peeling force by the surface state of a to-be-adhered body. Therefore, the operation | work which peels a protective film from an adherend (for example, a polarizing plate) can be performed efficiently. Although the minimum of S1 / S2 is not specifically limited, Usually, S1 / S2> 1, and typically S1 / S2≥1.1.

As a method which can be employ | adopted suitably in order to reduce S1 / S2 of a surface protection film, the method of including the oxypropylene group containing compound mentioned later in an adhesive layer is illustrated. As another method which helps to lower S1 / S2, making the thickness of an adhesive layer smaller, increasing the usage-amount of a crosslinking agent, adding a desired additive, etc. are mentioned. These methods can be employ | adopted individually or in combination suitably.

Next, the acrylic polymer which is a base polymer (the main component in a polymer component, ie, a component which occupies 50 mass% or more) of the adhesive layer in the technique disclosed here is demonstrated. Herein, the "acrylic polymer" refers to a monomer having at least one (meth) acryloyl group in one molecule (hereinafter, this may be referred to as an "acrylic monomer") as the main constituent monomer component (the main component of the monomer, that is, the acrylic system). The polymer used as a component which occupies 50 mass% or more in the total amount of the monomer which comprises a polymer is pointed out. Especially, the acryl-type polymer which makes alkyl (meth) acrylate the main structural monomer component is preferable.

In addition, in this specification, a "(meth) acryloyl group" means the acryloyl group and the methacryloyl group comprehensively. Similarly, "(meth) acrylate" is a meaning which refers to acrylate and methacrylate comprehensively.

As alkyl (meth) acrylate, the compound represented by following formula (1) can be used suitably, for example.

Here, in Formula 1, R ¹ is a hydrogen atom or a methyl group. R ² is an alkyl group having 1 to 20 carbon atoms. The alkyl group may be linear or may have a branch. As a specific example of the alkyl (meth) acrylate represented by General formula (1), n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, Pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (Meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylic Laterate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, Nonadecyl (meth) acrylic And eicosyl (meth) acrylate. Since the pressure-sensitive adhesive property is excellent pressure-sensitive adhesive easily be obtained, an alkyl (meth) alkyl group of R ² of which the number of carbon atoms from 2 to 14 (in the case shown below, such a range of number of carbon atoms, such as C _2-14) Acrylate is preferable, and alkyl (meth) acrylate whose R <^2> is _C4-10 alkyl group (for example, n-butyl group, 2-ethylhexyl group etc.) is more preferable.

In one preferable aspect, it is about 50 mass% or more (typically 50-99.9 mass%) in the total amount of the alkyl (meth) acrylate used for the synthesis | combination of an acrylic polymer, More preferably, it is 70 mass% or more (typically from 70 to 99.9% by weight), for example, about 85 mass% or more (typically 85 to 99.9% by weight) is, the R ² in the above formula (I) selected from alkyl (meth) acrylates of C _2-14 It is occupied by one kind or two or more kinds. According to the acrylic polymer obtained from such a monomer composition, since the adhesive which shows favorable adhesive characteristics is easy to be formed, it is preferable.

In one more preferable aspect, in the total amount of alkyl (meth) acrylate used for the synthesis of the acrylic polymer, approximately 50% by mass or more (typically 50 to 99.9% by mass), more preferably 70% by mass or more (typically Is 70 to 99.9% by mass), for example, approximately 85% by mass or more (typically 85 to 99.9% by mass), wherein R ² in the general formula (1) is an alkyl (meth) acrylate of C _6-14 Occupied. Since the acrylic polymer which has such a monomer composition tends to give a suitable adhesive for surface protection films, it is preferable. For example, since it becomes easy to control the peeling force from a to-be-adhered body low, the adhesive excellent in removability is easy to be obtained. For example, the composition whose R <^2> in the said General formula (1) is _C6-14 alkylacrylate (for example, 2-ethylhexyl acrylate) can be employ | adopted preferably.

As an acrylic polymer in the technique disclosed here, what copolymerized the acrylic monomer which has a hydroxyl group (-OH) can be used preferably. As a specific example of the acryl-type monomer which has a hydroxyl group, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) Acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyhexyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxy Oxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl acrylate, polypropylene glycol mono (meth) acrylate, N-hydroxyethyl (meth ) Acrylamide, N-hydroxypropyl (meth) acrylamide, etc. are mentioned. These hydroxyl-containing acrylic monomers may be used individually by 1 type, and may be used in combination of 2 or more type. The acrylic polymer copolymerized with such a monomer is preferable because it easily tends to impart a suitable adhesive for the surface protection film. For example, since it can become easy to control the peeling force with respect to a to-be-adhered body low, the adhesive excellent in removability is easy to be obtained. As a particularly preferable hydroxyl group containing acrylic monomer, (meth) acrylate containing a hydroxyl group, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl ( Meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate.

It is preferable that such a hydroxyl-containing acrylic monomer is used in the range of about 0.1-15 mass% in the total amount of the monomer used for the synthesis | combination of an acrylic polymer, The range of about 0.2-10 mass% is more preferable, About 0.3- The range of 8 mass% is especially preferable. When there is too much content of a hydroxyl-containing acrylic monomer than the said range, the cohesion force of an adhesive may become large too much, and fluidity | liquidity may fall, and wettability (adhesiveness) with respect to a to-be-adhered body may fall. On the other hand, when content of a hydroxyl-containing acrylic monomer is too small than the said range, the use effect of the said monomer may become difficult to fully be exhibited.

As the acrylic polymer in the technique disclosed herein, since it is easy to balance the adhesion performance, a glass transition temperature (Tg) of about 0 ° C or less (typically -100 ° C to 0 ° C) is usually used. Tg The acrylic polymer in the range of about -100 degreeC --5 degreeC is preferable, and it is more preferable that it is in the range of -80 degreeC --10 degreeC. When Tg is too high than the said range, initial stage adhesiveness will become easy to run short in use at normal temperature vicinity, and the workability of adhesion of a protective film may fall. Moreover, the value of the preferable compression creep characteristic (indentation distortion and / or distortion recovery coefficient) disclosed here may become difficult to realize. In addition, Tg of an acrylic polymer can be calculated | required by the glass transition temperature measuring method as described in the Example mentioned later. The value of this Tg can be adjusted by changing suitably the monomer composition (namely, the kind and usage-amount ratio of the monomer used for the synthesis | combination of the said polymer) of an acryl-type polymer.

The monomer (other monomer) of that excepting the above may be copolymerized in the acryl-type polymer in the technique disclosed here in the range which does not impair the effect of this invention remarkably. Such a monomer can be used, for example, for the purpose of adjusting Tg of an acrylic polymer, adjusting adhesion performance (for example, peelability), etc. For example, a sulfonic acid group containing monomer, a phosphoric acid group containing monomer, a cyano group containing monomer, vinyl esters, an aromatic vinyl compound etc. are mentioned as a monomer which can improve the cohesion force and heat resistance of an adhesive. Moreover, as a monomer which may introduce | transduce the functional group which may be a crosslinking origin into an acrylic polymer, or may contribute to the improvement of adhesive force, a carboxyl group containing monomer, an acid anhydride group containing monomer, an amide group containing monomer, an amino group containing monomer, an imide group containing monomer , An epoxy group-containing monomer, (meth) acryloyl morpholine, vinyl ethers, and the like.

As the sulfonic acid group-containing monomer, styrenesulfonic acid, allylsulfonic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, (meth) acrylamidopropanesulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxy Naphthalene sulfonic acid, sodium vinyl sulfonate, etc. are illustrated. 2-hydroxyethyl acryloyl phosphate is illustrated as a phosphoric acid group containing monomer. Acrylonitrile, methacrylonitrile, etc. are illustrated as a cyano group containing monomer. As vinyl ester, vinyl acetate, a vinyl propionate, a vinyl laurate etc. are illustrated, for example. As an aromatic vinyl compound, styrene, chloro styrene, chloromethyl styrene, (alpha) -methylstyrene, other substituted styrene, etc. are illustrated.

Moreover, as a carboxyl group-containing monomer, (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc. are illustrated. As an acid anhydride group containing monomer, maleic anhydride, itaconic anhydride, the acid anhydride body of the said carboxyl group-containing monomer, etc. are mentioned. As an amide group containing monomer, acrylamide, methacrylamide, diethyl acrylamide, N-vinylpyrrolidone, N, N-dimethyl acrylamide, N, N-dimethyl methacrylamide, N, N-diethyl acrylamide , N, N-diethyl methacrylamide, N, N'-methylenebisacrylamide, N, N-dimethylaminopropylacrylamide, N, N-dimethylaminopropyl methacrylamide, diacetone acrylamide, etc. are illustrated. . Examples of the amino group-containing monomers include aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, and the like. Examples of the imide group-containing monomer include cyclohexyl maleimide, isopropyl maleimide, N-cyclohexyl maleimide, itaciconimide and the like. As an epoxy group containing monomer, glycidyl (meth) acrylate, methylglycidyl (meth) acrylate, allyl glycidyl ether, etc. are illustrated. As vinyl ether, methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, etc. are illustrated.

Such "other monomers" may be used alone or in combination of two or more thereof, but the overall content is approximately 40% by mass or less in the total amount of the monomers used for the synthesis of the acrylic polymer (typically 0.001 It is preferable to set it as 40-40 mass%, and it is more preferable to set it as about 30 mass% or less (typically 0.001-30 mass%). Alternatively, only C _6-14 alkyl (meth) acrylate may be used as the monomer composition (eg, monomer, or C _6-14 alkyl (meth) acrylate and hydroxyl group-containing (meth) containing no other monomer. The acrylic polymer) which uses only an acrylate may be sufficient.

In addition, when using the monomer which has acid functional groups, such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group (for example, an acrylic monomer which has such an acid functional group) as said other monomer, the acid value of an acrylic polymer is about 29 or less (more preferable) Preferably at most 16, more preferably at most 8, particularly preferably at most 4). Thereby, the phenomenon which the adhesive force (advancing, peeling force from a to-be-adhered body) of a protective film adhering to a to-be-adhered body raises with time is suppressed, and favorable re-peelability can be maintained. The acid value of an acrylic polymer can be adjusted with the usage-amount (namely, monomer composition) etc. of the monomer which has an acid functional group. For example, in the case of the acrylic polymer which uses only 2-ethylhexyl acrylate and acrylic acid as a monomer, the acrylic polymer which satisfy | fills acid value 29 or less by making the quantity of acrylic acid 3.7 mass part or less out of 100 mass parts of total amounts of these monomers. Can be obtained. Or you do not need to use the monomer which has an acid functional group substantially. In one aspect of the surface protection film disclosed here, the said protective film is equipped with the adhesive layer which uses the acrylic polymer in which the monomer which has an acid functional group is not copolymerized substantially as a base polymer.

It is preferable that the weight average molecular weight of the acrylic polymer in the technique disclosed here exists in the range of 10 * 10 <^4> or more and 500 * 10 <^4> , More preferably, it is 20 * 10 <^4> or more and 400 * 10 <^4> or less, Furthermore Preferably it is 30 * 10 <^4> or more and 300 * 10 <^4> or less. Here, a weight average molecular weight (Mw) means the value of polystyrene conversion obtained by gel permeation chromatography (GPC). When Mw is too small than the said range, the cohesion force of an adhesive may run short and it may become easy to generate | occur | produce glue residue on the to-be-adhered surface. On the other hand, when Mw is too large than the said range, the fluidity | liquidity of an adhesive will become low, and the value of the preferable compression creep characteristic (indentation distortion and / or distortion recovery coefficient) disclosed here is implement | achieved in the surface protection film provided with the said adhesive. It can be difficult.

The method of obtaining the acrylic polymer which has such a monomer composition is not specifically limited, The said polymer can be obtained by applying various polymerization methods generally used as a synthesis | combining method of acrylic polymers, such as solution polymerization, emulsion polymerization, block polymerization, suspension polymerization, etc. . In addition, a random copolymer may be sufficient as the said acrylic polymer, and a block copolymer, a graft copolymer, etc. may be sufficient as it. From a viewpoint of productivity etc., a random copolymer is usually preferable.

The adhesive layer in the technique disclosed here can be normally formed using the adhesive composition containing the acrylic polymer as mentioned above normally. This adhesive composition is typically comprised so that the said acrylic polymer can be bridge | crosslinked suitably. By such crosslinking, a pressure-sensitive adhesive layer having a particularly suitable performance for a surface protective film can be formed. As a specific crosslinking means, a crosslinking origin is introduced into an acrylic polymer by copolymerizing a monomer having a suitable functional group (hydroxyl group, carboxyl group, etc.), and a compound (crosslinking agent) capable of reacting with the functional group to form a crosslinked structure is added to the acrylic polymer. Can be preferably employed. As a crosslinking agent, various materials used for crosslinking of a general acrylic polymer, for example, an isocyanate compound, an epoxy compound, a melamine resin, an aziridine compound, and the like can be used. Such a crosslinking agent may be used individually by 1 type, and may be used in combination of 2 or more type.

As a crosslinking agent used for the said adhesive composition, since the surface protection film which realizes the value of the preferable compression creep characteristic (indentation distortion and / or distortion recovery coefficient) disclosed here is easy to be obtained, and it is easy to adjust the said compression creep characteristic, And isocyanate compounds are particularly preferred. Moreover, use of an isocyanate compound is also preferable at the point which is easy to adjust the peeling force from a to-be-adhered body to an appropriate range. Examples of such isocyanate compounds include: aromatic isocyanates such as tolylene diisocyanate and xylene diisocyanate; Alicyclic isocyanates such as isophorone diisocyanate; Aliphatic isocyanates such as hexamethylene diisocyanate; Etc. can be mentioned. More specifically: Lower aliphatic polyisocyanates, such as butylene diisocyanate and hexamethylene diisocyanate; Alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; Aromatic diisocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate and xylylene diisocyanate; Trimethylolpropane / tolylene diisocyanate trimer adduct (made by Nippon Polyurethane Co., Ltd., brand name "colonate L"), trimethylolpropane / hexamethylene diisocyanate trimer adduct (made by Nippon Polyurethane Co., Ltd., brand name "colonate HL Isocyanate adducts, such as the isocyanurate body of hexamethylene diisocyanate (made by Nippon Polyurethane Co., Ltd., brand name "colonate HX"); Etc. can be illustrated. Such an isocyanate compound may be used individually by 1 type, and may be used in combination of 2 or more type.

Moreover, as an epoxy compound used as a crosslinking agent, N, N, N ', N'- tetraglycidyl-m-xylenediamine (made by Mitsubishi Gas Chemical Corporation, brand name "TETRAD-X"), 1, 3-bis ( N, N- diglycidylaminomethyl) cyclohexane (made by Mitsubishi Gas Chemicals, brand name "TETRAD-C") etc. are illustrated. As melamine type resin, hexamethylol melamine etc. are illustrated. As an aziridine derivative, a brand name "HDU", the same "TAZM", the same "TAZO", etc. made by Sogo Pharmaceutical Co., Ltd. are mentioned as a commercial item.

The usage-amount of a crosslinking agent can be suitably selected according to the composition and structure (molecular weight, etc.) of an acrylic polymer, the use form of a surface protection film, etc. Usually, it is suitable to use about 0.01-15 mass parts of crosslinking agents with respect to 100 mass parts of acrylic polymers, It is preferable to set it as about 0.1-10 mass parts (for example, about 0.2-5 mass parts), about 0.2 About 2 mass parts is more preferable. When the usage-amount of a crosslinking agent is too small, the cohesion force of an adhesive may run short and it may become easy to generate | occur | produce glue residue to a to-be-adhered body. On the other hand, when the usage-amount of a crosslinking agent is too big | large, the cohesion force of an adhesive may be large and fluidity will become low, and it may become difficult to realize the value of the preferable compression creep characteristic (indentation distortion and / or distortion recovery coefficient) disclosed here.

Moreover, as another crosslinking means, the method of mix | blending the polyfunctional monomer which has two or more radiation reactive functional groups in one molecule, and irradiating this to a radiation crosslinks (cures) an acrylic polymer is illustrated. As a radiation reactive functional group, unsaturated groups, such as a vinyl group, acryloyl group, a methacryloyl group, and a vinyl benzyl group, are illustrated. Usually, polyfunctional monomers having 10 or less (for example, 2 to 6) of radioactive functional groups per molecule are preferably used. These polyfunctional monomers may be used individually by 1 type, and may be used in combination of 2 or more type.

Specific examples of the polyfunctional monomers include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and 1,6- Hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, divinylbenzene, N, N'-methylene Bisacrylamide etc. are mentioned.

The usage-amount of a polyfunctional monomer can be suitably selected according to the composition and structure (molecular weight, etc.) of an acrylic polymer, the use form of a surface protection film, etc. Usually, it is suitable to mix | blend 0.1-30 mass parts of polyfunctional monomers with respect to 100 mass parts of acrylic polymers. In the use which emphasizes more flexibility and adhesiveness, what is necessary is just to make the compounding quantity of the polyfunctional monomer with respect to 100 mass parts of acrylic polymers to 10 mass parts or less (for example, 0.1-10 mass parts).

Examples of the radiation that can be used for the crosslinking reaction include ultraviolet rays, laser rays, α rays, β rays, γ rays, X rays, electron beams, and the like. In view of good controllability and handleability, and cost, usually ultraviolet rays (for example, ultraviolet rays having a wavelength of about 200 to 400 nm) are suitably used. Appropriate light sources, such as a high pressure mercury lamp, a microwave excited lamp, and a chemical lamp, can be used for irradiation of such an ultraviolet-ray.

When using an ultraviolet-ray as a radiation, it is preferable to add a photoinitiator to an adhesive composition normally. As such a photoinitiator, according to the kind of radiation reactive functional group contained in an adhesive composition, the substance which produces | generates a radical (photo radical polymerization initiator) or a cation which produces radicals by irradiating the ultraviolet-ray of the suitable wavelength which may be an occasion of the polymerization reaction can be produced. A substance (photo cationic polymerization initiator) can be used.

Examples of the radical photopolymerization initiator include: benzoin such as benzoin, benzoin methyl ether, benzoin ethyl ether, o-benzoyl benzoate methyl-p-benzoin ethyl ether, benzoin isopropyl ether and α-methylbenzoin; Acetophenones such as benzyl dimethyl ketal, trichloracetophenone, 2,2-diethoxy acetophenone, and 1-hydroxycyclohexylphenyl ketone; Propiophenones such as 2-hydroxy-2-methylpropiophenone and 2-hydroxy-4'-isopropyl-2-methylpropiophenone; Benzophenones such as benzophenone, methyl benzophenone, p-chlorobenzophenone and p-dimethylaminobenzophenone; Thioxanthones, such as 2-chloro thioxanthone, 2-ethyl thioxanthone, and 2-isopropyl thioxanthone; Acyl phosphines, such as bis (2, 4, 6- trimethyl benzoyl)-phenyl phosphine oxide, 2, 4, 6- trimethyl benzoyl diphenyl phosphine oxide, and 2, 4, 6- trimethyl benzoyl ethoxy phenyl phosphine oxide Oxides; In addition, benzyl, dibenzosuberon, (alpha)-acyl oxime ester, etc. are mentioned.

Examples of the photo cationic polymerization initiator include: onium salts such as aromatic diazonium salts, aromatic iodonium salts and aromatic sulfonium salts; Organometallic complexes such as iron-alene complexes, titanocene complexes, and arylsilanol-aluminum complexes; In addition, nitrobenzyl ester, sulfonic acid derivative, phosphate ester, phenol sulfonic acid ester, diazonaphthoquinone, N-hydroxyimidosulfonate, etc. are mentioned.

Such a photoinitiator may be used individually by 1 type, and may be used in combination of 2 or more type. The usage-amount of a photoinitiator can be about 0.1-10 mass parts with respect to 100 mass parts of acrylic polymers, for example. Usually, it is preferable to mix | blend about 0.2-7 mass parts of photoinitiators with respect to 100 mass parts of acrylic polymers.

Moreover, it is also possible to use together photoinitiation | polymerization adjuvant, such as amines. As such a photoinitiation adjuvant, 2-dimethylamino ethyl benzoate, dimethyl amino acetophenone, p-dimethyl amino benzoic acid ethyl ester, p-dimethyl amino benzoic acid isoamyl ester, etc. are mentioned. Such photopolymerization start adjuvant may be used individually by 1 type, and may be used in combination of 2 or more type. It is preferable that the usage-amount of a photoinitiator adjuvant shall be about 0.05-10 mass parts (for example, about 0.1-7 mass parts) with respect to 100 mass parts of acrylic polymers.

The pressure-sensitive adhesive composition may further contain a crosslinking catalyst for more effectively promoting any of the above-described crosslinking reactions. As such a crosslinking catalyst, for example, a tin catalyst (particularly dibutyltin dilaurate) can be preferably used. Although the usage-amount of a crosslinking catalyst (for example, tin type catalysts, such as dibutyltin dilaurate) is not restrict | limited, For example, it can be made into about 0.005-1 mass part with respect to 100 mass parts of acrylic polymers. For example, the use of an isocyanate crosslinking agent and a tin crosslinking catalyst is preferable.

In a preferable embodiment of the technique disclosed herein, the pressure-sensitive adhesive layer has a structure in which, in addition to the acrylic polymer as the base polymer, a portion in which two or more units of oxypropylene units are continuous (that is,-(OC ₃ H ₆ ) _n- Moiety containing an oxypropylene group-containing compound having n ≧ 2). Hereinafter, the part in which two or more oxypropylene units continued may be called "polyoxypropylene segment." In addition, there is a case that the oxyethylene unit at least a portion of the continuous two units called "polyoxyethylene segments" (-OC ₂ H ₄ - -, typically a -OCH ₂ CH _2). By containing such an oxypropylene group containing compound in an adhesive layer as needed, peeling force S1 with respect to the TAC polarizing plate which is not AG surface-treated can be reduced more than peeling force S2 with respect to AG-treated TAC polarizing plate. Thereby, peeling force ratio S2 / S1 can be reduced and it can adjust so that preferable S2 / S1 disclosed here may be obtained. That is, use of the said oxypropylene group containing compound is a suitable example of the method which can be employ | adopted as needed in order to implement | achieve S2 / S1 <= 2.

As said oxypropylene group containing compound, various well-known materials which have the said structure can be used individually or in combination suitably. For example, polypropylene glycol (PPG), a compound containing an oxypropylene unit and an oxyethylene unit (the arrangement of these units may be random or block-like), derivatives thereof and the like can be used. As PPG, what has molecular structure, such as a diol type, a triol type, and a hexanol type, can be used. As a compound (which may be a compound having a polyoxypropylene segment and a polyoxyethylene segment) containing an oxypropylene unit and an oxyethylene unit, it is preferable that the number of oxypropylene units occupies 50% or more among these total unit numbers. As a specific example of such a compound, a PPG- polyethyleneglycol (PEG) -PPG block copolymer, a PPG-PEG block copolymer, a PEG-PPG-PEG block copolymer, etc. are mentioned. As said derivative, the oxypropylene group containing compound (PPG monoalkyl ether, PEG-PPG monoalkyl ether, etc.) which the terminal was etherified is mentioned.

The said oxypropylene group containing compound is typically used by adding and mixing to the acrylic polymer previously polymerized (synthesized). Therefore, unlike the case where such a compound is used as a copolymerization component of the acrylic polymer, an oxypropylene group-containing compound having a structure that does not have a radical polymerizable functional group (for example, acryloyl group, methacryloyl group, etc.) is preferably used. It can be adopted. As especially preferable oxypropylene group containing compound in this invention, a diol type or a triol type PPG is mentioned. Especially, use of diol type PPG is preferable.

As said oxypropylene group containing compound, a number average molecular weight is about 0.2 * 10 <^3> -10 * 10 <^3> (more preferably about 0.2 * 10 <^3> -5 * 10 <^3> , for example, about 1 * 10 <^3> 5 * 10 It is used preferably in the range of ³ ). The number average molecular weight (Mn) means the value of polystyrene conversion obtained by GPC here. When Mn is too low than the said range, the effect of reducing the difference of peeling force by the surface state of a to-be-adhered body (for example, the effect of making the value of the said peeling force ratio close to 1) may become difficult to fully exhibit. . When Mn is too high than the said range, there exists a tendency for the compatibility of an acryl-type polymer and an oxypropylene group containing compound to run short, and the transparency of an adhesive layer may fall, or the level of non-contamination with respect to a to-be-adhered body may fall. Can be.

The usage-amount (mixing amount) of the oxypropylene group containing compound with respect to 100 mass parts of acrylic polymers can be about 0.01-10 mass parts, for example, Preferably it is about 0.03-5 mass parts, More preferably, it is about 0.05-3 It is a mass part. When the usage-amount of an oxypropylene group containing compound is too small than the said range, the effect of adjusting peeling force ratio S2 / S1 (typically making S2 / S1 smaller) may become difficult to fully be exhibited. When the usage-amount of an oxypropylene group containing compound is too much larger than the said range, the level of non-contamination with respect to a to-be-adhered body may become a tendency to fall.

In the technique disclosed here, the adhesive composition used for formation of an adhesive layer can contain various conventionally well-known additives as needed. Examples of such additives include surface lubricants, leveling agents, antioxidants, preservatives, light stabilizers, ultraviolet absorbers, polymerization inhibitors, silane coupling agents, inorganic or organic fillers, and the like. Moreover, you may mix | blend a well-known or common tackifying resin in the adhesive composition which uses an acrylic polymer as a base polymer.

The support body which comprises the surface protection film disclosed here can be various synthetic resin films (plastic films), paper, a nonwoven fabric. From the standpoint of excellent surface protection function, it is usually preferable to use a synthetic resin film as a support. The material (resin material) which comprises such a synthetic resin film should just be what can be shape | molded in a sheet form or a film form, and is not specifically limited. For example: polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-vinyl acetate copolymer, ethylene-ethylacrylic Polyolefin films such as a rate copolymer and an ethylene-vinyl alcohol copolymer; Polyester films such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate; Polyamide films such as nylon 6, nylon 6,6 and partially aromatic polyamides; In addition, a synthetic resin film composed of a resin material such as a polyacrylate film, a polystyrene film, a polyvinyl chloride film, a polyvinylidene chloride film, a polycarbonate film (a single layer structure may be used, and two or more layers having different materials may be Lamination | stacking structure may be included). Especially, use of a polyester film (typically, a polyethylene terephthalate film) is preferable. Although the thickness of a support body can be suitably selected according to the objective, it is usually about 5 micrometers-about 200 micrometers, Preferably it is about 10 micrometers-about 100 micrometers. It is preferable to make thickness of a support body into about 20 micrometers-60 micrometers from a viewpoint that the surface protection film which satisfy | fills the said characteristic (A), (B) is easy to be obtained.

As needed, various additives, such as filler (inorganic filler, organic filler, etc.), an antioxidant, antioxidant, a ultraviolet absorber, a lubricating agent, a plasticizer, a coloring agent (pigment, dye, etc.), may be mix | blended with the said synthetic resin film. On the surface of the support (particularly, the surface on which the pressure-sensitive adhesive layer is formed), for example, known or conventional surface treatment such as acid treatment, alkali treatment, corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, application of a primer, etc. May be implemented. Such surface treatment can be a process for improving adhesiveness (the adhesiveness of an adhesive layer) of an adhesive layer and a support body, for example. In addition, the support may be subjected to mold release or contamination prevention treatment using a conventionally known mold release agent (for example, silicone based, fluorine based, long chain alkyl based, fatty acid amide based, etc.) or silica powder.

As a support body of the surface protection film disclosed here, what consists of a charged synthetic resin film can be employ | adopted preferably. The method of antistatic treatment is not specifically limited, For example, the method of forming an antistatic layer in the at least single side | surface of a film, the method of mixing an antistatic agent in a film, etc. can be used.

As a method of forming an antistatic layer on at least one side of a film, For example: The method of apply | coating the antistatic coat agent containing an antistatic agent and the resin component used as needed; A method of applying a conductive coating agent containing a conductive polymer and other resin components used as necessary; A method of depositing or plating a conductive material; Etc. can be mentioned.

Examples of the antistatic agent (antistatic component) contained in the antistatic coating agent include: cationic antistatic agents having cationic functional groups such as quaternary ammonium salts, pyridinium salts, first, second or tertiary amino groups. ; Anion type antistatic agent which has anionic functional groups, such as a sulfonate, a sulfate ester salt, a phosphonate salt, and a phosphate ester salt; Zwitterionic antistatic agents such as alkylbetaines and derivatives thereof, imidazolines and derivatives thereof, alanine and derivatives thereof; Nonionic antistatic agents such as aminoalcohol and its derivatives, glycerin and its derivatives, polyethylene glycol and its derivatives; Furthermore, the ion conductive polymer obtained by superposing | polymerizing or copolymerizing the monomer which has the said cationic, anionic, and zwitterionic ion-conductive group; Etc. can be mentioned. Such an antistatic agent may be used individually by 1 type, and may be used in combination of 2 or more type.

Specific examples of the cationic antistatic agent include: acrylic copolymers having quaternary ammonium groups such as alkyltrimethylammonium salts, acyloylamidopropyltrimethylammonium methosulfate, alkylbenzylmethylammonium salts, acyl chloride and polydimethylaminoethyl methacrylate. ; Styrene copolymers having quaternary ammonium groups such as polyvinylbenzyltrimethylammonium chloride; Diallylamine copolymers having quaternary ammonium groups such as polydiallyldimethylammonium chloride; Etc. can be mentioned. Specific examples of the anion type antistatic agent include alkyl sulfonates, alkylbenzene sulfonates, alkyl sulfate ester salts, alkyl ethoxy sulfate ester salts, alkyl phosphate ester salts, sulfonic acid group-containing styrene copolymers, and the like. Specific examples of the zwitterionic antistatic agent include alkyl betaines, alkyl imidazolium betaines, carbo betaine graft copolymers, and the like.

Specific examples of nonionic antistatic agents include fatty acid alkylolamides, di (2-hydroxyethyl) alkylamines, polyoxyethylene alkylamines, fatty acid glycerin esters, polyoxyethylene glycol fatty acid esters, sorbitan fatty acid esters, and polyoxysorbers. Non-fatty acid ester, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ether, polyethylene glycol, polyoxyethylene diamine, the copolymer which consists of polyether, polyester, and polyamide, a methoxy polyethylene glycol (meth) acrylate, etc. are mentioned. Can be.

As an electroconductive polymer, polyaniline, polypyrrole, polythiophene, etc. are mentioned, for example. Such a conductive polymer may be used individually by 1 type, and may be used in combination of 2 or more type.

Examples of the conductive material include tin oxide, antimony oxide, indium oxide, cadmium oxide, titanium oxide, zinc oxide, indium, tin, antimony, gold, silver, copper, aluminum, nickel, chromium, titanium, iron, cobalt, Copper iodide and their alloys or mixtures. Such an electroconductive substance may be used individually by 1 type, and may be used in combination of 2 or more type.

As a resin component used for an antistatic coating agent or a conductive coating agent, general-purpose resins, such as a polyester resin, an acrylic resin, a polyvinyl resin, a urethane resin, a melamine resin, an epoxy resin, are used, for example. In addition, in the case of a polymer type antistatic agent, use of a resin component can be abbreviate | omitted. In addition, the antistatic coating agent may contain a methylolated or alkylolated melamine, urea, glyoxal, acrylamide or the like, an epoxy compound, an isocyanate compound or the like as the crosslinking agent of the resin component.

The antistatic coating agent or conductive coating agent, the antistatic component (antistatic agent or conductive polymer as described above) and the resin component used as necessary is dispersed in a suitable solvent (organic solvent, water or a mixed solvent thereof). Or in the form of a dissolved liquid composition. As a formation method of an antistatic layer, the method of apply | coating and drying the said liquid composition to a synthetic resin film can be employ | adopted preferably, for example. As an organic solvent which comprises the said liquid composition, for example, methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran (THF), dioxane, cyclohexanone, n-hexane, toluene, xylene, methanol, ethanol, n Propanol, isopropanol, etc. are mentioned. These solvents may be used independently, or may mix and use 2 or more types.

As a method of apply | coating the liquid composition for antistatic layer formation, a well-known coating method can be used suitably. As a specific example, the roll coating method, the gravure coating method, the reverse coating method, the roll brush method, the spray coating method, the air knife coating method, the impregnation method, and the curtain coating method are mentioned. The thickness of the antistatic layer is usually preferably approximately 0.01 µm to 5 µm, and preferably approximately 0.03 µm to 1 µm.

When the antistatic layer is formed by vapor deposition or plating of a conductive material, conventionally known methods such as vacuum deposition, sputtering, ion plating, chemical vapor deposition, spray pyrolysis, chemical plating, and electroplating methods may be appropriately used as the vapor deposition or plating method. It can be adopted. As thickness of the conductive material layer formed by such a method, about 20 kPa-about 10000 kPa are suitable normally, and about 50 kPa-5000 kPa are preferable.

In the antistatic treatment of the method in which the antistatic agent is incorporated into the film, the antistatic agent (antistatic agent for mixing) to be used may be the same as the above-described material as the antistatic agent used for the formation of the antistatic layer. Can be. The compounding quantity of such an antistatic agent can be made into about 20 mass% or less (typically 0.05-20 mass%) with respect to the gross mass of a film, for example, Usually, it shall be made into the range of 0.05-10 mass%. It is suitable. The mixing method of the antistatic agent is not particularly limited as long as it is a method capable of uniformly mixing the antistatic agent with the synthetic resin material for film formation. For example, a heating roll, a Banbury mixer, a pressure kneader, a biaxial kneader, or the like is used. The method of kneading using is mentioned.

The adhesive layer which comprises the surface protection film disclosed here can be suitably formed by giving the above-mentioned adhesive composition on a predetermined surface, and drying or hardening. For example, the method (direct method) which forms an adhesive layer on the said support body by apply | coating an adhesive composition directly to a support body, and drying or hardening; A method of forming a pressure-sensitive adhesive layer on the surface by applying the pressure-sensitive adhesive composition to the surface (peeled surface) of the release liner and drying or curing, bonding the pressure-sensitive adhesive layer to the support, and transferring the pressure-sensitive adhesive layer to the support (transcription method); Etc. can be employed. From the viewpoint of the adhesiveness of the pressure-sensitive adhesive layer, usually the above-mentioned direct method can be preferably adopted. In the provision (typically application) of the pressure-sensitive adhesive composition, a field of pressure-sensitive adhesive sheets such as a roll coating method, a gravure coating method, a reverse coating method, a roll brush method, a spray coating method, an air knife coating method and a coating method by a die coater In the related art, various conventionally known methods can be appropriately employed. The thickness of an adhesive layer can be about 3 micrometers-about 100 micrometers, for example, and about 5 micrometers-about 50 micrometers are preferable normally. It is preferable to make thickness of an adhesive layer into 10 micrometers-40 micrometers from a viewpoint which the surface protection film which satisfy | fills the said characteristic (A), (B) is easy to be obtained.

The surface protection film disclosed here is the form (surface which has a peeling liner) which bonded the peeling liner to the said adhesive surface for the purpose of protecting an adhesive surface (surface of the side adhered to a to-be-adhered body in an adhesive layer) as needed. In the form of a protective film). As a base material which comprises a peeling liner, paper, a synthetic resin film, etc. can be used, A synthetic resin film is used suitably from the point which is excellent in surface smoothness. For example, the synthetic resin film which consists of resin materials like a support body can be used suitably as a base material of a peeling liner. The thickness of a release liner can be made into about 5 micrometers-200 micrometers, for example, and about 10 micrometers-about 100 micrometers are preferable normally. The surface bonded to the pressure-sensitive adhesive layer in the release liner may be subjected to mold release or contamination prevention treatment using a conventionally known mold release agent (for example, silicone-based, fluorine-based, long-chain alkyl-based, fatty acid amide-based, etc.) or silica powder. do.

The surface protection film disclosed here may satisfy | fill 1 or 2 or more of the following characteristics further.

(C) After 30 minutes of crimping | bonding the said surface protection film to the AG surface of a polarizing plate, the area exceeding 99.0% in an adhesive layer is in close contact with the said polarizing plate. That is, adhesiveness with respect to AG surface is larger than 99.0%. Since such a surface protection film shows the outstanding adhesiveness with respect to the uneven surface (for example, AG surface of a polarizing plate), even if it receives external force or temperature change, a change of an external appearance can be highly suppressed. In more preferable aspect of the surface protection film disclosed here, the said adhesiveness is 99.5% or more (and 99.7% or more). In addition, the said adhesiveness can be evaluated by the method similar to the Example mentioned later, for example.

(D) In the peeling force measurement performed by the method described in the Example mentioned later, peeling force S1 with respect to a TAC polarizing plate is 3 N / 25 mm or less (typically 1-3 N / 25 mm). The surface protection film in which S1 exists in the said range has the favorable balance of protective performance and peeling workability.

(E) In peeling force measurement performed by the method as described in the Example mentioned later, peeling force S2 with respect to AG polarizing plate is 0.5-2N / 25mm. The surface protection film in which S2 exists in the said range has the favorable balance of protective performance and peeling workability.

<Examples>

Hereinafter, although some Example concerning this invention is described, it is not what intended limiting this invention to what is shown by this specific example. In addition, "part" and "%" are mass references | standards unless there is particular notice in the following description. In addition, in the following description, each characteristic was measured as follows, respectively.

[Measurement of Acid Value]

The acid value was measured using an automatic titrator (COM-550, manufactured by Hiranuma Sangyo Co., Ltd.) and determined from the following formula.

A = {(Y-X) × f × 5.611} / M

A; Acid

Y; Amount of titration solution required for titration of sample solution (mL)

X; Quantity of titration solution (mL) required for titration of mixed solvent (50 g)

f; Factor of titration solution

M; Mass of polymer sample (g)

Measurement conditions are as follows.

Sample solution: About 0.5 g of a polymer sample was dissolved in 50 g of a mixed solvent (mixing toluene / 2-propanol / distilled water at a mass ratio of 50 / 49.5 / 0.5) to prepare a sample solution.

Titration solution: 0.1 N, 2-propanolated potassium hydroxide solution (made by Wako Pure Chemical Industries, Ltd., for petroleum products neutralization test)

Electrode: glass electrode; GE-101, comparison electrode; RE-201

Measuring Mode: Petroleum Product Neutralization Test 1

[Measurement of molecular weight]

The molecular weight was measured using a GPC device (manufactured by Tosoh Corporation, HLC-8220GPC). Measurement conditions are as follows. In addition, molecular weight was calculated | required by polystyrene conversion value.

Sample concentration: 0.2 mass% (THF solution)

Sample injection volume: 10 μL

Eluent: THF

Flow rate: 0.6mL / min

Measuring temperature: 40 ℃

column:

Sample column; TSK guard column Super HZ-H (1 piece) + TSK gel Super HZM-H (2 pieces)

Reference column; TSK Gel Super H-RC (1)

Detector: Differential Refractometer (RI)

[Measurement of Glass Transition Temperature]

Glass transition temperature (Tg) (degreeC) was calculated | required by the following method using the dynamic-viscoelasticity measuring apparatus (ARES, the product made by Leometrics). That is, the sheet | seat (thickness: 20 micrometers) of an acryl-type polymer was laminated | stacked, it was made into thickness of about 2 mm, it was punched to the circular shape of diameter 7.9 mm, and the cylindrical pellet was produced. This pellet was used as a sample for measuring glass transition temperature. The measurement sample is fixed to a jig (parallel plate having a diameter of 7.9 mm), the temperature dependence of the loss modulus G ″ is measured by the dynamic viscoelasticity measuring device, and the temperature at which the obtained G ″ curve is maximized is determined by the glass transition temperature (° C). ). Measurement conditions are as follows.

Measurement: Shear Mode

Temperature range: -70 to 150 ° C

Temperature rise rate: 5 ℃ / min

Frequency: 1 Hz

<Example 1>

In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, a cooler and a dropping funnel, 200 parts of 2-ethylhexyl acrylate, 8 parts of 2-hydroxyethyl acrylate and 2,2'-azo as a polymerization initiator 0.4 part of bisisobutyronitrile and 312 parts of ethyl acetate were thrown in, nitrogen gas was introduce | transduced with gentle stirring, and the liquid temperature in a flask was kept at 60 degreeC, and it polymerized for 5 hours, and the solution of the acrylic polymer A (solid content (NV) 40%) was prepared. The weight average molecular weight (Mw) of this acrylic polymer A was 55x10 <^4> , glass transition temperature (Tg) was -55 degreeC and acid value was 0.0.

Ethyl acetate was added to the solution of acrylic polymer A (NV 40%), and diluted to NV 20%. 0.1 part of diol-type polypropylene glycol (PPG) (made by Wako Pure Chemical Industries, Ltd.) whose number average molecular weight (Mn) is about 3000 with respect to 100 parts of this solution, and the trimethylolpropane / tolylene diisocyanate trimer adduct as a crosslinking agent (Nippon 0.6 part of polyurethane high grade products, brand name "collonate L", 75% ethyl acetate solution), and 0.4 part of dibutyltin dilaurate (1% ethyl acetate solution) as a crosslinking catalyst are added, and it is for about 1 minute under normal temperature (25 degreeC). The mixture was stirred to prepare pressure-sensitive adhesive composition B1.

On the other hand, an antistatic agent solution was prepared by diluting 10 parts of an antistatic agent (manufactured by Solvex Inc., microsolver RMd-142, tin oxide and polyester resin as main components) with a 30/70 (mass ratio) mixed solvent of water and methanol. It was. This antistatic agent solution was apply | coated to the single side | surface of a 38-micrometer-thick polyethylene terephthalate (PET) film using a Mayer bar, and the solvent was removed by heating at 130 degreeC for 1 minute, and the antistatic layer of thickness 0.2micrometer was formed. In this way, an antistatic PET film was produced.

Adhesive composition B1 was apply | coated to the surface opposite to the antistatic treatment surface of the said antistatic treatment film, and it heated at 110 degreeC for 3 minutes, and formed the adhesive layer of 20 micrometers in thickness. Subsequently, the siliconized surface (peeled surface) of 25-micrometer-thick PET film (peeling liner) by which siliconization was given to the surface of the said adhesive layer was bonded. Thus, the adhesive sheet C1 of the form which has an adhesive layer in the single side | surface of an antistatic process film (support body), and the said adhesive layer was protected by the peeling liner was obtained.

<Example 2>

In Example 1, the amount of PPG added was changed to 0.05 parts. About the other points, the adhesive composition B2 was produced like Example 1, and the adhesive sheet C2 was produced using this composition B2.

<Example 3>

Ethyl acetate was added to the solution of acrylic polymer A (NV 40%), and it diluted to NV 20%. 0.2 part of PPG as used in Example 1, 0.4 part of isocyanurates of hexamethylene diisocyanate as a crosslinking agent (made by Nippon Polyurethane Co., Ltd., brand name "collonate HX") with respect to 100 parts of this solution, and a crosslinking catalyst 0.3 part of dibutyltin dilaurate (1% ethyl acetate solution) was added, and it mixed and stirred for 1 minute at normal temperature (25 degreeC), and prepared adhesive composition B3. Except having used this adhesive composition B3, it carried out similarly to Example 1, and produced the adhesive sheet C3.

<Example 4>

In Example 3, the amount of the crosslinking agent was changed to 0.6 parts, and the amount of PPG added was changed to 0.02 parts. About other points, it carried out similarly to Example 3, and produced adhesive composition B4, and produced adhesive sheet C4 using this composition B4.

<Example 5>

In Example 3, the amount of the crosslinking agent was changed to 0.8 part, and PPG was not used. About other points, it carried out similarly to Example 3, and produced adhesive composition B5, and produced adhesive sheet C5 using this composition B5.

<Example 6>

In Example 1, the amount of the crosslinking agent was changed to 0.8 part, and PPG was not used. About other points, it carried out similarly to Example 1, and produced adhesive composition B6, and produced adhesive sheet C6 using this composition B6.

<Example 7>

In Example 3, the amount of the crosslinking agent was changed to 0.6 parts, and PPG was not used. About other points, it carried out similarly to Example 3, and produced adhesive composition B7, and produced adhesive sheet C7 using this composition B7.

About the adhesive sheets C1 to C7 produced in Examples 1-7, the compression creep test, adhesive evaluation, and peeling force were measured with the following methods. Table 2 shows the result of the schematic structure of the adhesive composition used for preparation of the adhesive sheet which concerns on each example in Table 2.

[Compression Creep Test]

24 sheets of the pressure-sensitive adhesive sheets from which the release liner was removed were stacked to prepare a sample for compression creep test. The shape of the said sample was made into the square columnar shape whose bottom side is 10 mm. As a test apparatus, the dynamic viscoelasticity measuring apparatus and model "RSA III" made from TA Instruments Corporation were used. The amount of distortion (indentation distortion (E1) (%)) when a load of 0.195 MPa was applied to the sample for 10 minutes at a measurement temperature of 25 ° C. using a parallel jig having a tip diameter of 8 mm, and from the load The amount of distortion (permanent distortion (E2) (%)) after releasing after 10 minutes was measured. From these measurement results, the distortion recovery coefficient was calculated by E1 / E2.

Peeling force measurement

As a to-be-adhered body, two kinds of polarizing plates of the plane polarizing plate (TAC polarizing plate made by Nitto Denko Corporation, SEG1425DU) of width 70mm, length 100mm, and the same size polarizing plate (AG polarizing plate made by Nitto Denko Corporation, AGS1) to which AG coating was given Was prepared. The adhesive sheet was cut into a size of 25 mm in width and 100 mm in length of the release liner, and the release liner was removed to expose the adhesive surface. The adhesive surface was crimped | bonded to the said two types of polarizing plates at the pressure of 0.25 MPa, and the speed of 0.3 m / min, respectively. After leaving it for 30 minutes in an environment of 23 ° C. × 50% RH, the pressure-sensitive adhesive sheet was peeled from the polarizing plate under conditions of a peel rate of 30 m / min and a peel angle of 180 ° using a universal tensile tester under the same environment. Was measured. The results are shown in Table 2. In this table, TAC (S1) shows the peeling force with respect to a TAC polarizing plate, and AG (S2) shows the peeling force with respect to an AG polarizing plate.

[Adhesive evaluation]

As a to-be-adhered body, the polarizing plate (AG polarizing plate by Nitto Denko Corporation, AGS1 made from Nitto Denko Co., Ltd.) of width 50mm and length 60mm which AG coating was prepared was prepared. The pressure sensitive adhesive sheet was cut into a size of 40 mm in width and 50 mm in length of the release liner, and the release liner was removed to expose the adhesive surface. The adhesive surface was crimped | bonded to the said polarizing plate using the roll press machine at the pressure (linear pressure) of 0.15 Mpa, and the speed of 5.0 m / min. After 30 minutes had elapsed from the pressing, the pressure-sensitive adhesive sheet attached to the polarizing plate was observed at a magnification of 100 times from the back side (support side) using a digital microscope manufactured by Giens. More specifically, the image data obtained by the said microscope was binarized, and the ratio of the area which the said adhesive layer adheres to the surface of a polarizing plate among the areas of an adhesive layer was calculated | required.

[Appearance evaluation]

The tester pinched the polarizing plate which bonded the protective film with the finger, and after removing the finger, the visual difference of the part (non-contact part) which was not in contact with the part (contact part) which the finger contacted was visually observed, and It evaluated on the basis of.

○: no difference between contact and non-contact

(Triangle | delta): The difference is slightly recognized by the contact part and the non-contact part.

×: The car is clearly identified at the contact portion and the noncontact portion.

As shown in Table 1 and Table 2, the adhesive sheets according to Examples 1 to 4 satisfying the above-described characteristics (A) and (B) are all good (more specifically, more than 99.0%) with respect to the AG surface. Adhesion). As a result of peeling by hand the adhesive sheets which concerns on these Examples 1-4 to the said TAC polarizing plate and AG polarizing plate by hand, the difference of reaction by the kind of polarizing plate is not felt very much, and the magnitude | size of peeling force ratio S1 / S2 actually peels It was confirmed that the workability is well reflected. In addition, in the adhesive evaluation sheet which concerns on Examples 1-4, the external appearance difference was not confirmed between a contact part and a non-contact part in the said external appearance evaluation test.

On the other hand, the adhesive sheets which concerns on Examples 5-7 were all 99.0% or less. Moreover, as a result of peeling by hand the thing which adhered the adhesive sheet which concerns on Examples 5-7 to the said TAC polarizing plate and AG polarizing plate by hand, it was confirmed that peeling from a TAC polarizing plate is apparently severe compared with AG polarizing plate. In the adhesive sheet which concerns on Example 5, in the said external appearance evaluation test, the apparent difference in appearance was confirmed by the contact part and the non-contact part.

The adhesive composition for surface protection films disclosed here can be used suitably for use, such as formation of the adhesive (typically adhesive layer) with which various surface protection films are provided, manufacture of the surface protection film with such an adhesive, etc. . In addition, the surface protection film disclosed here uses the said optical member at the time of manufacture of an optical member used as components, such as a liquid crystal display, a plasma display panel (PDP), an organic electroluminescent (EL) display, conveyance, etc. It is suitable for protecting applications. In particular, it is useful as a surface protection film applied to optical members, such as a polarizing plate (polarizing film) for liquid crystal displays, a wave plate, a retardation plate, an optical compensation film, a brightness enhancement film, a light-diffusion sheet, and a reflection sheet.

Claims (7)

It is a surface protection film provided with a support body and the adhesive layer which is provided in one side of the said support body and uses an acrylic polymer as a base polymer, The surface protection film which satisfy | fills the following conditions.
(A) Indentation distortion (E1) of the laminated body in which 24 sheets of said surface protection films were laminated | stacked is 7.0% or more, and ratio (E1 / E2) with respect to permanent distortion (E2) of the said indentation distortion (E1) is 30 or less. . Here, the initial thickness of the laminate is T0, and the indentation distortion E1 is obtained by applying a compressive stress of 0.195 MPa in the thickness direction for 10 minutes by inserting the laminate into a circular plane having a diameter of 8 mm at 25 ° C. The reduction ratio from the initial thickness T0 of the thickness T1, and the permanent distortion (E2) is the reduction ratio from the initial thickness T0 of the thickness T2 when 10 minutes have elapsed after releasing the laminate from the compressive stress; And
(B) The said surface protection film is peeling force S1 with respect to the triacetyl cellulose polarizing plate which is not antiglare in the peeling force measurement performed on the conditions of measurement temperature 23 degreeC, peeling speed 30m / min, and peeling angle 180 degreeC. It is 2 times or less of peeling force S2 with respect to the antiglare triacetylcellulose polarizing plate. The surface protection film of Claim 1 in which the area | region exceeding 99.0% of the said adhesive layer is in close contact with the said polarizing plate after 30 minutes of crimping | bonding the said surface protection film to the said antiglare triacetylcellulose polarizing plate. . The surface protective film according to claim 1, wherein the pressure-sensitive adhesive layer includes a compound having a polyoxypropylene segment in which two or more oxypropylene units are continuous in addition to the acrylic polymer. The said protective layer is a surface protection film of Claim 1 in which the said acrylic polymer was bridge | crosslinked with the isocyanate type crosslinking agent. The surface protection film of Claim 1 whose thickness of the said adhesive layer is 10 micrometers-40 micrometers. The surface protective film of claim 1, wherein the support is a polyester film having a thickness of 20 μm to 60 μm. The surface protection film of Claim 1 in which the said support body consists of a synthetic resin film to which the antistatic process was given.

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